Method for treating a solid particulate material with a fluid



51' 2,1979 HQNQHAR 3,529,

METHOD FOR TREATING A SOLID PARTICULATE MATERIAL WITH A FLUID OriginalFiled June 17, 1966 Memllized Ore Feeder L22 (Wmer) INVEN'TOR Andrew P.vHonchur w g x AGENT U.S. Cl. 23-202 3 Claims ABSTRACT OF THE DISCLOSUREThe instant invention relates in general to a method and apparatus forcontacting a fluid with a solid for the purpose of altering thecomposition of the solid and in particular to a method and apparatus forcontinuously leaching a metallized titaniferous iron ore with an acid todissolve and remove the iron values and recover a titanium concentratesuitable for chlorination in the production of TiCl This application isa division of US. application Ser. No. 558,337, filed June 17, 1966, andnow US. 3,468,633, issued Sept. 23, 1969.

There are of course, many types of operations involving contact of agranular solid with a fluid, examples of which may be found in thefields of absorption, ionexchange, crystallization and the like. Inthese operations both co-current and countercurrent flow of the solidand fluid materials may be found. In those instances in whichcountercurrent flow has been used, i.e. where the solid particles flowby gravity downwardly against an upwardly flowing fluid, variousmechanical devices have been resorted to in order to produce a downwardflow of the solids against the uplifting effect of the fluid. Thesemechanical devices, however, have numerous disadvantages including costof construction and operation, mechanical Wear, breakage, etc.

Other expedients for controlling the solids include the use of asupplementary flow of liquid downwardly, cocurrently with the flow ofsolids or the use of vertical tubes connecting successive treatingchambers. Despite the fact that the latter devices have no moving partsthey are relatively complex and hence subject to frequentmalfunctioning. Moreover, they are relatively inefficient in as much asthey permit contamination of partially treated solids with untreatedsolids; and further, embody no means for controlling the retention timeof the solids at any one treating zone independently of the othertreating zone.

An object of the present invention is to provide an improved process andapparatus for treating solids with fluids in an eflicient, economicaland dependable manner.

A further object of the invention is to provide improvements overpreviously known methods and apparatus for treating solid particulatematerial with fluid treating agents wherein the solid particulatematerial is treated in increments and the treatment of each increment iseffected independently of every other increment.

Another object of the invention is to provide superior method and meansfor continuously leaching metallized ilmenite ore with an acid toproduce a TiO concentrate suitable for chlorination feed material in theproduction of titanium tetrachloride.

These and other objects, features and advantages of the invention willbe described and illustrated in more detail below and by the drawings inwhich:

FIG. 1 is a schematic vertical elevation, of apparatus nited StatesPatent 3,529,933 Patented Sept. 22, 1970 for carrying out the process ofthis invention showing the treating tower and means for controlling theflow of solids to the several successive treating zones of the tower;

FIG. 2 is an enlarged side elevation partly in section of two of thefunnel-shaped shelves in successive treating zones of the leachingtower;

FIG. 3 is an enlarged schematic elevation partly in section, of amodified fluid flow control device for use with the funnel-shapedshelves of the tower; and

FIG. 4 is a transverse section on line 44 of FIG. 3

' showing details of the modified fluid flow control device.

In general the present invention relates to an improved method andapparatus for treating solid particulate materials with a fluid in whichthe fluid flows in a direction countercurrent to the direction of flowof the solid particulate material by subjecting the particulate materialfirst to a roughing-treatment and then to a finishingtreatment, thefinishing-treatment being characterized by passing the particulatematerial by gravity feed through at least one and preferably a pluralityof segregated treating zones in each of which a separate increment ofthe solid material is subjected to treatment by said fluid, theretention time in each treating zone being independent of that at everyother treating zone and controlled by effecting a change in the linearflow velocity of fluid at each treating zone.

As pointed out above among the many applications of the instantinvention may be included absorption towers, ion-exchange processes,chlorination techniques ore digestion and the like but for the purposeof illustrating the instant invention the following description relatesto a method and means for leaching a metallized titaniferous iron orewith a mineral acid to produce a chlorination feed material suitable.for use in the production of TiCl It will be understood however thatthis embodiment of the invention is for illustration purposes only andthat the invention contemplates all applications and modificationsthereof within the scope of the appended claims.

The method of the instant invention may be described more specificallyas comprising the steps of: feeding a solid particulate material i.e.metallized ilmenite ore by gravity feed into the top of an uprightleaching tower characterized by a rough-leaching section and a finishleaching section, the rough-leaching section being at the upper end ofthe tower; feeding a leach fluid, i.e. sulfuric acid at a constant rateof flow into the lower end of the tower for passage upwardly thereinthrough the finishleaching section into the rough-leaching section ofthe tower where the acid attacks the incoming metallized ore and leachesout a major portion .of the iron fraction; thereafter allowing theincompletely leached ore to flow by gravity into the finish-leachingsection of the tower there to effect removal of the residual ironfraction by providing at least one and preferably a plurality ofsuperimposed leaching zones in the finishing-section of said tower eachleaching zone being characterized by a funnelshaped shelf having anever-open outlet; maintaining the linear velocity of the acid flowingupwardly through the ever-open outlets of said shelves, normally,sufiicient to retain segregated portions of the incompletely leached orein fluid or turbulent motion on said shelves for further leaching;selectively reducing the linear velocity of the acid flowing through anyone of the ever-open outlets of said shelves, independently of theothers, to effect release of the ore from the corresponding shelf forgravity flow downwardly through its ever-open outlet to the next lowershelf for further leaching, and varying the retention time of the ore ateach leaching zone by varying the length of time the acid flows upwardlyat its normal linear velocity through the ever-open outlet of thecorresponding shelf.

The process of this invention is designed especially for leaching ametallized ore continuously, the leached ore being dischargedcontinuously or intermittently, from the lower end of the tower afterpassing through a washing zone; and the spent acid being dischargedcontinuously from the upper end of the tower. In this particularapplication of the invention wherein a metallized ilmenite ore isleached with sulfuric acid, hydrogen gas is evolved and rises up throughthe tower into a gas chamber provided above the rough-leaching sectionof the tower there to escape by way of a suitable exhaust port. Since itis important that the collection and removal of the hydrogen gas becarefully controlled and that none escapes from the gas chamber into theatmosphere the process of this invention also includes feeding themetallized ore into the upper end of the leaching tower through aliquid-seal which is maintained within the gas chamber to preclude theescape of the hydrogen gas to the atmosphere.

Referring now to the drawings, the apparatus embodies, in general, aleaching tower into which the metallized ore is fed for leaching;equipment for feeding the metallized ore and the leaching acid to thetower; means for washing the leached ore before being discharged fromthe tower; and means for recovering the spent acid and any gasesgenerated during leaching. The leaching tower, which is designatedgenerally at 10, is a sealed unit made of a corrosion resistant materialsuch as a suitable ceramic, Pyrex glass, silica or suitable alloymetals. The tower is preferably although not necessarily substantiallycylindrical, having an enlargement 11 at its upper end which identifiesthe rough-leaching section of the tower, the portion of the tower belowthe rough-leaching section being somewhat smaller diameter andidentified with the finishleaching section 12 of the tower. The lowerend of the finish-leaching section 12 comprises a pipe-section 13 ofrelatively small diameter below which is a washing-section 14 of largerdiameter having a lateral water-inlet pipe with valve 15, a water-outletpipe with valve 16, and a discharge-pipe with valve 17. The water-inletand outlet pipes are used to circulate water through the washingsection14 for subjecting leached ore therein to a washing treatment beforebeing discharged from the washing-section. A valve 18 is provided at thelower extremity of the pipe-section 13 for shutting off this sectionfrom the washing-section 14; also an inlet pipe 19 is provided in thepipe-section 13 for introducing the leaching acid into the lower end ofthe leaching tower. As mentioned above, the tower is adapted to besealed from the atmosphere and to this end is provided with a cover 20at its upper end. Also the several valves of the tower are madegastight.

Reverting again to the rough-leaching section 11 of the tower, here themetallized ore is first brought into contact with the leach acid andinasmuch as the amount of metallic iron in the reduced ore is maximumthe reaction of the acid with the iron is extremely rapid and hence isaccompanied by the generation of large volumes of hydrogen gas whichcreates severe turbulence of the oreacid mixture. To alford some measureof control of the ore-acid mixture during this rough-leaching step aplurality of perforated plates 21 are provided in this section of thetower to act as bafiies for damping the severe agitation of the ore-acidmixture.

As mentioned above the finish-leaching section 12 of the tower isdivided into a plurality of super-imposed leaching zones 22 each beingcharacterized by a funnelshaped shelf 23 formed of a corrosion resistantmaterial such as antimony lead.

As shown especially well in FIG. 2 each funnel-shaped shelf has anever-open outlet 24 at its apex for discharging ore therefrom to thenext lower shelf as hereinafter described. Each funnel-shaped shelf 23is also provided with a small aperture or weep-hole 25 in its walladjacent the intersection thereof with the wall of the tower to permitthe hydrogen gas evolved during leaching of the ore to pass upwardly inthe tower through the successive leaching zones 22 into a gas chamber 26provided in the enlarged rough-leaching section 11 of the tower abovethe level of the acid therein. In this connection a lateral dischargepipe 27 is provided in the gas chamber 26 to permit the discharge of thehydrogen gas and spent acid from the tower, the spent acid and thehydrogen gas being separated by a T-connection 28 at the outer end ofthe discharge pipe 27.

As pointed out above an inlet pipe 19 is provided for feeding the leachacid into the lower end of the tower for passage upwardly therein and tothis end a pump 29, or its equivalent, is provided for pumping the acidat a uniform rate of flow into the tower. Consistent With the objects ofthe instant invention, the rate of flow of the acid into the tower, inliters/min, is related to the diameters of the ever-open outlets of thefunnel-shaped shelves in the finish-leaching section of the tower suchthat, normally, the linear velocity of the acid flowing up through theever-open outlets of the shelves is sufficient to prevent the ore on theshelves from flowing downwardly therethrough. Moreover the linearvelocity of the acid may be such as to actually create turbulence of theore on or above' the shelves thereby effecting a more efficient leachingaction.

Referring again to FIG. 2 that latter shows one embodiment of the meansused for initiating flow of the ore downwardly through the ever-openoutlets of the funnelshaped shelves against the upwardly flowing acid.In this embodiment each funnel-shaped shelf is provided with avalved-aperture 30, formed about midway up the wall of the shelf, havinga valve 31 and valve actuating means 32. Each valve actuating means 32comprises a rod extending laterally through an apertured T in the Wallof the tower and is adapted to be operated either manually orautomatically to move its valve 31 to and from its correspondingaperture 30 to close or open the latter. In the case where the actuatingmeans 32 is operated automatically it is connected into suitablecircuitry including timer 33 and electrically or pneumatically ac tuatedsolenoids indicated generally at 34 for operating each valve 31 in timedsequence.

Normally the valved apertures 30 of the funnel-shaped shelves are heldclosed by the corresponding actuating means 32 and under thesecircumstances the linear velocity of the acid flowing upwardly throughthe ever-open outlets of the shelves is suflicient to prevent the orethereon from flowing down through the ever-open outlets to the nextlower shelves. However when any one of the valves 31 is opened acid willflow upwardly through its aperture 30 as a consequence of which thelinear velocity of the acid flowing up through the ever-open outlet 24of the corresponding shelf is lowered thus permitting the ore thereon toflow down therethrough. It will be evident from the drawing that eachfunnel-shaped shelf is provided with its own valved-aperture 30 andcontrol means therefore and hence it follows that the retention of theore on each shelf is independent both in sequence of operation and timefrom that of any other shelf.

As mentioned above, the metallized ore is adapted to be fed into the topof the leaching tower by way of a liquid-seal to prevent the escape ofhydrogen gas from the tower. To this end an ore feed tube 35 is arrangedto extend through the cover 20 of the tower with a gas tight seal downinto the gas chamber 26 to a point therein below the level of thesulfuric acid in the rough-leaching section 11 of the tower. Due to adifference between the hydrostatic pressure in the gas chamber 26 and inthe ore feed tube 35 the sulfuric acid will rise up into the ore feedtube above the level of the acid in the gas chamber thus forming aliquid seal in the feed tube 35 which permits the metallized ore to befed continuously into the upper end of the leaching tower whileexcluding the escape of hydrogen gas therefrom. Any suitable means maybe used for feeding the metallized ore into the feed tube 35. Preferablythe ore feeder which is indicated schematically at 36, should be capableof measuring the ore feed rate. Moreover experience has shown that auniform flow of ore into the feed tube is assured by providing a funnel37 at the upper end of the feed tube and maintaining a spray of waterand/ or dilute acid therein from spray head 38 to prevent the ore frombridging and to continuously flush it down into the feed tube.

The operation of the leaching column may be described briefly asfollows:

Prior to feeding the metallized ore to the leaching tower the valve 18at the lower end of the finish-leaching section is closed shutting itoff from the washing zone 14, and pump 29 is started to pump dilutesulphuric acid at a uniform rate into the bottom of the tower filling itup to the level of the discharge pipe 27 at which time some of thedilute acid rises up in the lower end of the ore feed tube 35 to formthe aforementioned liquid-seal. Metallized ore together with water fromthe spray head 38 is now fed by way of the feed tube 35 into theroughleaching section 11 of the tower where a relatively violentleaching action takes place accompanied by the dissolution of a majorportion of the metallic iron in the ore. The violence of this reactionsends the ore particles down through the perforated plates 21 into thefinish-leaching section 12 of the tower. At the outset thevalved-apertures 30 of the shelves 23 are closed and hence, as explainedabove, the linear velocity of the acid flowing up through the ever-openoutlets 24 of the shelves is such that the metallized ore flowing downfrom the rough-leaching sec-. tion into the top side of the uppermostfunnel-shaped shelf is held from passing down through its ever-openoutlet 24. Following a predetermined interval during which anappreciable amount of metallized ore is accumulated on the topmostshelf, its valved-aperture 30 is opened by actuation of its valveoperating rod 32 as a consequence of which the linear velocity of theacid flowing up through the ever-open outlet 24 is decreased therebyallowing the ore to flow by gravity feed therethrough to the next lowershelf. If the valved aperture 30 of the next lower shelf is closed, thenthe partially leached ore from the uper shelf will be retained thereonuntil such times as its valved aperture 30 is opened whereupon theleached ore will flow by gravity down to the next lower shelf. Thus anincrement of incompletely leached ore moves continuously, by jerks, orintervals, from the topmost shelf of the finish-leaching section of thetower to the bottom thereof; and at each self or leaching zone the oreincrement may beretained for a predetermined length of timeindependently of the ore increment at other shelf levels, and withoutbeing contaminated by fresh or partially leached ore from the leachingzone above.

As the leached ore passes through the ever-open outlet 24 of thelowermost shelf it accumulates in the pipesection 13 of the tower whereit is subjected to additional leaching by the acid therein; and in thisconnection it will be observed that at this point in the tower the acidconcentration is strongest and hence is especially effective in leachingthe last traces of metallic iron from the ore.

During the operation of the leaching tower the reaction of the acid withthe metallic iron in the ore creates hydrogen gas and this rises upcontinuously through the leaching tower from one leaching zone to thenext through the weep-holes 25 provided in each shelf and collects inthe gas chamber 26 from which it escapes together with the spent acidvia the discharge pipe 27.

Pursuant to further objects of the invention the fully leached ore iswashed before being discharged from the tower. To this end the dischargevalve 17 of the washing-section 14 is closed and the water-inlet valve15 and outlet valve 16 are opened to permit water to circulate throughthe washing section 14 whereupon the valve 18 of the pipe-section 13 isopened to permit the "fully leached ore to flow down into thewashing-section 14. The valve 18 is then closed and after a selectedtime interval during which the leached ore is thoroughly washed thewater inlet valve 15 is closed and the discharge valve 17 is opened toallow the washed fully leached ore to be discharged from the tower. Byusing this system of valves and sequence of operations each batch offully leached ore may be thoroughly washed without interrupting the flowof acid into the lower end of the finish-leaching section of the tower.

Referring again to the drawings, FIGS. 3 and 4 show a modification ofthe means used for initiating the flow of ore downwardly through thefinish-leaching section against the upwardly flowing acid. In thisembodiment of the invention each shelf is provided with an ever-openoutlet 24; and mounted immediately below and in contact therewith is ashutter 40. As shown especially well in FIG. 4 the latter is ofconventional design comprising a fixed plate 41 and movable plate 42said plates having V-shaped notches in opposed edges for defining anaperture 43. The movable plate 42 is provided with an operating rod 44,corresponding to the valve operating rods 32 shown in FIG. 2, to varythe size of the aperture 43 and hence the effective size of theever-open outlet of each shelf for effecting an increase or decrease inthe linear velocity of the acid flowing upwardly therethrough.

As mentioned at the outset the tower is sealed from the atmosphere andhence may be operated at atmospheric pressures or at pressures aboveatmospheric the latter being conductive of higher dissolution ofleachables and superior TiO concentrates.

The following examples will serve to further illustrate the method andapparatus of this invention as used for the production of a TiOconcentrate from a metallized ilmenite ore.

EXAMPLE I The leaching tower which, for purposes of illustrating theinvention was approximately 13 ft. high about 6 inches in diameter atits rough-finishing section and about 3 inches in diameter through itsfinish-leaching section, was first purged with nitrogen gas to displaceany entrained air in the system. Valve 18 being closed, acid pump 29 wasstarted to feed dilute sulfuric acid (12% H at 70 C. via feed pipe 19into the bottom of the tower at a uniform rate of approximately 483.0ml. per minute. The metallized ore to be used was a magnetic fractionproduced by heating an ilmenite ore in the presence of a reductant andpassing the reduced ore through a magnetic separator to effectseparation of the non-magnetic gangue material. The gangue-free magneticmaterial had the following analysis:

TABLE I Analysis of gangue-free magnetic fraction of metallized orePercent TiO 55.3 Fe (total) 40.3 Fe (metallic) 38.7 Metallization 96.0

390 lbs. of this metallized ore were fed from the feeder 36 into theleaching tower at the rate of 19.1 lbs. per hour and simultaneously thewater spray head 38 was started to feed water into the funnel 37 of theore feed tube 35 at the rate of 1,400 ml. per minute.

The leaching zones in the finish-leaching section of the tower consistedof three equally spaced superimposed funnel-shaped shelves the walls ofwhich made an angle of about 86 with the horizontal and the ever-openoutlets of which were in diameter.

With the acid being pumped into the tower at a uniform rate of 483.0 ml.per min. the linear velocity of the leaching acid upwardly through theever-open outlets of the several shelves was 0.52 ft./sec. At thislinear veloc- 7 ity the metallized ore was retained in a fluidized stateon each shelf.

At start-up the metallized ore was fed into the roughleaching section 11of the tower where it was retained for 20 minutes after which the timer33 was started to effect the sequential transfer of the incompletelyleached ore downwardly by gravity feed into the finish-leaching sectionof the tower. The timer was set so that the total elapsed leaching timefor each increment of metallized Ore from one leaching zone or shelf tothe next was 10 minutes of which 4 minutes was drop time.

Both the valve 17 and the valve 18 were closed at startup and after aperiod of about 35 minutes, corresponding to the total retention time ofa given increment of ore in the leaching tower, water-inlet and outletvalves 15 and 16 were opened to circulate water through thewashingsection 14. Valve 18 was then opened to permit the fully leachedore to flow down into the washing-section 14 whereupon the valve 18 wasclosed and the ore was retained in the washing-section for about 60minutes for thorough washing after which water inlet valve 15 was closedand outlet valve 17 was opened thereby discharging the fully leached,washed concentrate from the tower.

The residual leach liquor in the concentrate was removed by furtherwashing and filtration and the resulting TiO concentrate was then driedby heating to 375 F. for about 12 hours.

At this point it may be mentioned that materials suitable for use aschlorination feed in the production of titanium tetrachloride are thosewhich contain high amounts of TiO and low amounts of otherchlorinatables and in particular iron, an ideal chlorination feedmaterial being an unground rutile ore concentrate comprising at least90.0% T102, and from 0.5 to 2.0% iron and having a particle size rangeof from 40 to +150 mesh by Standard Tyler screens.

An analysis Was made of the T iO concentrate produced as hereinabovedescribed and showed 92.2% TiO and 1.4% total iron. Moreover there wasno significant diminution in particle size during leaching and hence theconcentrate was suitable for use as a chlorination feed material for theproduction of TiCl EXAMPLES II-V Several additional runs were made usinga metallized ore of the type described in Example I but under somewhatdifferent operating conditions. These operating conditions are tabulatedin Table II below, together with the analyses of the TiO concentratesproduced.

TABLE II.LEACH COLUMN OPERATING DATA Examples I II III IV Ore charge(lbs) 390.0 518.0 669. 536. 0 Ore feed rate (lbs. per hour) 19. 1 15.015. 0 15. 0 ILISO4 (feed rate ml/m in.) 483. O 440. 0 444.0 440. 0 1120to ore feed (ml/mm.) H. 1, 400. 0 1,308. 0 1, 358. 0 1, 440. 0 Ore:retention time in column (min. 35. 0 35. 0 35. 0 35. 0 IIrSB 4 linearvelocity in conical apex (it./see.) 0. 52 0. 43 0. 43 0. 45 Temp. (H2804C.) 70. 0 66. 0 65. 0 74. 0 Total running time (hrs.) 20. 0 34.0 40. 035.0 Concentrate:

Total titanium as T102, percent 92. 2 92. 3 92. 5 92. 9 Total ironoxides as Fe(t), percent 4 1. 7 1. 5 1. 2

From the foregoing description and examples it is evident that theleaching column of the instant invention provides an eflicient,dependable and relatively inexpensive method for treating a solidparticulate material with a fluid; and in particular for leaching ametallized ilmenite ore with an acid to produce a TiO concentratesuitable for use as feed material in the production of TiCl While theleaching may be done as a batch type operation the preferred operationis a continuous one wherein the metallized ore if fed continuously intothe top of the leaching column and the washed TiO concentrate isdischarged continuously, or intermittently, from the bottom thereof.

The invention may be carried out in other specific ways than thoseherein set forth without departing from the spirit and essentialcharacteristics of the invention; and the present embodiments aretherefore to be considered in all respects as illustrative and notrestrictive, and all changes coming within the meaning and equivalencyrange of the appended claims are intended to be embraced there- What isclaimed is: 1. Method for leaching a gangue-free metallized titaniferousore, said metallized portion principally consisting of elemental iron,with dilute sulfuric acid solution by fluid-solid contact to selectivelydissolve and remove the iron values and recover a titanium dioxideconcentrate, comprising the steps of:

(a) feeding said metallized ore initially to a roughleaching zone andthen to a plurality of superimposed finish-leaching zones havingever-open outlets;

(b) feeding said dilute sulfuric acid solution continuously and at auniform rate of flow upwardly through said superimposed finish-leachingzones in a direction countercurrent to the gravity feed of saidmetallized ore to fluidize and leach said ore, the leaching of said orebeing accompanied by the evolution of hydrogen (c) maintaining thelinear velocity of said acid upwardly through the ever-open outlets of.said finishleaching zones sufficient to retain segregated portions ofsaid metallized ore at said finish-leaching zones;

(d) reducing the linear velocity of said acid through the ever-openoutlets of any one finish-leaching zone sufficiently to release thecorresponding segregated portion of said metallized ore for gravity flowto the next lower finish-leaching zones;

(e) bleeding said hydrogen gas from the finish-leaching zones upwardlyinto the rough-leaching zone;

(f) discharging the leached ore from the lowermost finish-leaching zone;

(g) discharging the spent acid from the rough-leaching zone;

(h) and maintaining a liquid seal between the acid being discharged fromthe rough-leaching zone and the metallized ore being fed thereto.

2. Method according to claim 1 wherein the liquid seal between the acidand the metallized ore is maintained by supporting a column of liquid inthe rough-leaching zone and feeding the metallized ore thereto throughsaid column of liquid.

3. Method according to claim 1 wherein a washing zone is maintainedbelow the lowermost finish-leaching zone and the leached ore dischargedtherefrom is fed to said washing zone and washed.

References Cited UNITED STATES PATENTS 3,018,170 1/1962 Soloducha 23202XR 3,416,885 12/1968 Honchar 23202 XR 3,428,427 2/1969 Raiceric 23-1023,468,633 9/1969 Honchar 233 10 XR EDWARD STERN, Primary Examiner US.Cl. X.R.

